<template>
  <div ref="wrap">
    <div
      :style="leftSwitch"
      v-if="isHorizontal"
      :class="leftSwitchClass"
      @click="leftSwitchClick"
    >
      <slot name="left-switch"></slot>
    </div>
    <div
      :style="rightSwitch"
      v-if="isHorizontal"
      :class="rightSwitchClass"
      @click="rightSwitchClick"
    >
      <slot name="right-switch"></slot>
    </div>
    <div
      ref="realBox"
      :style="pos"
      @mouseenter="enter"
      @mouseleave="leave"
      @touchstart="touchStart"
      @touchmove="touchMove"
      @touchend="touchEnd"
    >
      <div ref="slotList" :style="float">
        <slot></slot>
      </div>
    </div>
  </div>
</template>
<script>
import "./animationFrame";
export default {
  name: "vue-seamless-scroll",
  data() {
    return {
      xPos: 0,
      yPos: 0,
      delay: 0,
      copyHtml: "",
      height: 0,
      width: 0, // 外容器宽度
      realBoxWidth: 0, // 内容实际宽度
      reqFrame: null, // move动画的animationFrame定时器
      singleWaitTime: null, // single 单步滚动的定时器
      isHover: false // mouseenter mouseleave 控制this._move()的开关
    };
  },
  props: {
    data: {
      type: Array,
      default: () => {
        return [];
      }
    },
    classOption: {
      type: Object,
      default: () => {
        return {};
      }
    }
  },
  computed: {
    leftSwitchState() {
      return this.xPos < 0;
    },
    rightSwitchState() {
      return Math.abs(this.xPos) < this.realBoxWidth - this.width;
    },
    leftSwitchClass() {
      return this.leftSwitchState ? "" : this.options.switchDisabledClass;
    },
    rightSwitchClass() {
      return this.rightSwitchState ? "" : this.options.switchDisabledClass;
    },
    leftSwitch() {
      return {
        position: "absolute",
        margin: `${this.height / 2}px 0 0 -${this.options.switchOffset}px`,
        transform: "translate(-100%,-50%)"
      };
    },
    rightSwitch() {
      return {
        position: "absolute",
        margin: `${this.height / 2}px 0 0 ${this.width +
          this.options.switchOffset}px`,
        transform: "translateY(-50%)"
      };
    },
    float() {
      return this.isHorizontal
        ? { float: "left", overflow: "hidden" }
        : { overflow: "hidden" };
    },
    pos() {
      return {
        transform: `translate(${this.xPos}px,${this.yPos}px)`,
        transition: `all ${this.ease || "ease-in"} ${this.delay}ms`,
        overflow: "hidden"
      };
    },
    defaultOption() {
      return {
        step: 1, // 步长
        limitMoveNum: 5, // 启动无缝滚动最小数据数
        hoverStop: true, // 是否启用鼠标hover控制
        direction: 1, // 0 往下 1 往上 2向左 3向右
        openTouch: true, // 开启移动端touch
        singleHeight: 0, // 单条数据高度有值hoverStop关闭
        singleWidth: 0, // 单条数据宽度有值hoverStop关闭
        waitTime: 1000, // 单步停止等待时间
        switchOffset: 30,
        autoPlay: true,
        switchSingleStep: 134,
        switchDelay: 400,
        switchDisabledClass: "disabled",
        isSingleRemUnit: false // singleWidth/singleHeight 是否开启rem度量
      };
    },
    options() {
      return Object.assign({}, this.defaultOption, this.classOption);
    },
    moveSwitch() {
      return this.data.length < this.options.limitMoveNum;
    },
    hoverStop() {
      return (
        !this.options.autoPlay || !this.options.hoverStop || this.moveSwitch
      );
    },
    canNotTouch() {
      return !this.options.openTouch || !this.options.autoPlay;
    },
    isHorizontal() {
      return this.options.direction > 1 || !this.options.autoPlay;
    },
    baseFontSize() {
      return this.options.isSingleRemUnit
        ? parseInt(
            window.getComputedStyle(document.documentElement, null).fontSize
          )
        : 1;
    },
    realSingleStopWidth() {
      return this.options.singleWidth * this.baseFontSize;
    },
    realSingleStopHeight() {
      return this.options.singleHeight * this.baseFontSize;
    }
  },
  methods: {
    leftSwitchClick() {
      if (!this.leftSwitchState) return;
      // 小于单步距离
      if (Math.abs(this.xPos) < this.options.switchSingleStep) {
        this.xPos = 0;
        return;
      }
      this.xPos += this.options.switchSingleStep;
    },
    rightSwitchClick() {
      if (!this.rightSwitchState) return;
      // 小于单步距离
      if (
        this.realBoxWidth - this.width + this.xPos <
        this.options.switchSingleStep
      ) {
        this.xPos = this.width - this.realBoxWidth;
        return;
      }
      this.xPos -= this.options.switchSingleStep;
    },
    _cancle() {
      cancelAnimationFrame(this.reqFrame || "");
    },
    touchStart(e) {
      if (this.canNotTouch) return;
      let timer;
      const touch = e.targetTouches[0]; // touches数组对象获得屏幕上所有的touch，取第一个touch
      this.startPos = {
        x: touch.pageX,
        y: touch.pageY
      }; // 取第一个touch的坐标值
      this.startPosY = this.yPos; // 记录touchStart时候的posY
      this.startPosX = this.xPos; // 记录touchStart时候的posX
      if (!!this.options.singleHeight && !!this.options.singleWidth) {
        if (timer) clearTimeout(timer);
        timer = setTimeout(() => {
          this._cancle();
        }, this.options.waitTime + 20);
      } else {
        this._cancle();
      }
    },
    touchMove(e) {
      // 当屏幕有多个touch或者页面被缩放过，就不执行move操作
      if (
        this.canNotTouch ||
        e.targetTouches.length > 1 ||
        (e.scale && e.scale !== 1)
      )
        return;
      const touch = e.targetTouches[0];
      this.endPos = {
        x: touch.pageX - this.startPos.x,
        y: touch.pageY - this.startPos.y
      };
      event.preventDefault(); // 阻止触摸事件的默认行为，即阻止滚屏
      const dir = Math.abs(this.endPos.x) < Math.abs(this.endPos.y) ? 1 : 0; // dir，1表示纵向滑动，0为横向滑动
      if (dir === 1 && this.options.direction < 2) {
        // 表示纵向滑动 && 运动方向为上下
        this.yPos = this.startPosY + this.endPos.y;
      } else if (dir === 0 && this.options.direction > 1) {
        // 为横向滑动 && 运动方向为左右
        this.xPos = this.startPosX + this.endPos.x;
      }
    },
    touchEnd() {
      if (this.canNotTouch) return;
      let timer = null;
      const direction = this.options.direction;
      this.delay = 50;
      if (direction === 1) {
        if (this.yPos > 0) this.yPos = 0;
      } else if (direction === 0) {
        const h = (this.$refs.realBox.offsetHeight / 2) * -1;
        if (this.yPos < h) this.yPos = h;
      } else if (direction === 2) {
        if (this.xPos > 0) this.xPos = 0;
      } else if (direction === 3) {
        const w = this.$refs.slotList.offsetWidth * -1;
        if (this.xPos < w) this.xPos = w;
      }
      if (timer) clearTimeout(timer);
      timer = setTimeout(() => {
        this.delay = 0;
        this._move();
      }, this.delay);
    },
    enter() {
      if (this.hoverStop) return;
      this.isHover = true; // 关闭_move
      // 防止蛋疼的人频频hover进出单步滚动 导致定时器乱掉
      if (this.singleWaitTime) clearTimeout(this.singleWaitTime);
      this._cancle();
    },
    leave() {
      if (this.hoverStop) return;
      this.isHover = false; // 开启_move
      this._move();
    },
    _move() {
      // 鼠标移入时拦截_move()
      if (this.isHover) return;
      this._cancle(); // 进入move立即先清除动画 防止频繁touchMove导致多动画同时进行
      this.reqFrame = requestAnimationFrame(
        function() {
          if (!this.$refs.realBox) return; // fixed 路由之间切换报this.$refs.realBox.offsetHeigh undefined bug
          const h = this.$refs.realBox.offsetHeight / 2; // 实际高度
          const w = this.$refs.slotList.offsetWidth; // 宽度
          const direction = this.options.direction; // 滚动方向
          if (direction === 1) {
            // 上
            if (Math.abs(this.yPos) >= h) {
              this.$emit("ScrollEnd");
              this.yPos = 0;
            }
            this.yPos -= this.options.step;
          } else if (direction === 0) {
            // 下
            if (this.yPos >= 0) {
              this.$emit("ScrollEnd");
              this.yPos = h * -1;
            }
            this.yPos += this.options.step;
          } else if (direction === 2) {
            // 左
            if (Math.abs(this.xPos) >= w) {
              this.$emit("ScrollEnd");
              this.xPos = 0;
            }
            this.xPos -= this.options.step;
          } else if (direction === 3) {
            // 右
            if (this.xPos >= 0) {
              this.$emit("ScrollEnd");
              this.xPos = w * -1;
            }
            this.xPos += this.options.step;
          }
          if (this.singleWaitTime) clearTimeout(this.singleWaitTime);
          if (this.realSingleStopHeight) {
            // 是否启动了单行暂停配置
            if (Math.abs(this.yPos) % this.realSingleStopHeight < 1) {
              // 符合条件暂停waitTime
              this.singleWaitTime = setTimeout(() => {
                this._move();
              }, this.options.waitTime);
            } else {
              this._move();
            }
          } else if (this.realSingleStopWidth) {
            if (Math.abs(this.xPos) % this.realSingleStopWidth < 1) {
              // 符合条件暂停waitTime
              this.singleWaitTime = setTimeout(() => {
                this._move();
              }, this.options.waitTime);
            } else {
              this._move();
            }
          } else {
            this._move();
          }
        }.bind(this)
      );
    },
    _initMove() {
      this.$nextTick(() => {
        this.height = this.$refs.wrap.offsetHeight;
        this.width = this.$refs.wrap.offsetWidth;
        // 水平滚动设置warp width
        if (this.isHorizontal) {
          let rate;
          if (!this.options.autoPlay) {
            rate = 1;
          } else {
            rate = 2;
          }
          const w = this.$refs.slotList.offsetWidth * rate;
          this.$refs.realBox.style.width = w + "px";
          this.realBoxWidth = w;
        }
        if (!this.options.autoPlay) {
          this.ease = "linear";
          this.delay = this.options.switchDelay;
          return;
        }
        this._dataWarm(this.data);
        this.copyHtml = ""; // 清空copy
        // 是否可以滚动判断
        if (this.moveSwitch) {
          this._cancle();
          this.yPos = this.xPos = 0;
        } else {
          let timer;
          if (timer) clearTimeout(timer);
          this.copyHtml = this.$refs.slotList.innerHTML;
          this._move();
        }
      });
    },
    _dataWarm(data) {
      if (data.length > 100) {
        console.warn(
          `数据达到了${data.length}条有点多哦~,可能会造成部分老旧浏览器卡顿。`
        );
      }
    }
  },
  mounted() {
    this._initMove();
  },
  watch: {
    data(newData, oldData) {
      this._dataWarm(newData);
      // 监听data是否有变更
    /*  if (!this.$_arrayEqual(newData, oldData)) {
        this._cancle();
        this._initMove();
      }*/
    }
  },
  beforeDestroy() {
    this._cancle();
  }
};
</script>
